1. Field of the Invention
The present invention relates generally to internal combustion engines, and more particularly to a method for sealing planetary rotor engines and the resulting dynamically formed seals. Planetary rotor engines include three or more rotors which are radially displaced from the center of the device and rotate together to alternately increase and decrease the volume of a chamber defined by the rotors, thereby defining three major junctures which require sealing.
2. Description of the Related Art
The best known general subtype of internal combustion engines is the reciprocating piston machine, which has been adapted for operation for innumerable applications. However, a lesser known configuration for internal combustion engines is the planetary rotor engine. Generally described, the planetary rotor engine comprises a plurality of radially displaced rotors which are keyed to a like number of shafts about a central chamber. The shape of the rotors is defined by four quadrantal arcs of a circle, with two opposite arcs having a relatively large radius and two arcs between the larger arcs, having relatively smaller radii. When the axes of the rotors are positioned on a circle with the major axes of the rotors oriented in the same direction and each of the rotors touching the two adjacent rotors, they define a volume captured between the rotors. When the rotors are rotated in the same direction and at the same rotational velocity, their shapes result in portions of their respective faces remaining in constant close proximity to one another at all times, and changing the volume defined by the rotors at a regular frequency occurring twice per rotor rotation. The rotors are rotated by harnessing explosive forces directed against the faces of the rotors forming the chamber, thereby translating them into useful mechanical energy.
However, in contrast to the better known and popular classes of internal combustion engines (i.e. gasoline piston, diesel piston, "Wankel" rotary-type, jet, etc.), such planetary rotor engines have a potential as a class to significantly advance the art of internal combustion engine technology for reasons inherent to its design. Such advantages include 1) a reduced weight and size ratio needed to produce a unit of power, 2) a reduction in number of parts, in turn permitting a wider RPM range, 3) a higher leverage ratio (i.e. greater torque from less pressure), each of which lead to further advantages useful to the consumer market, namely more work performed for less fuel consumption (i.e. greater fuel efficiency), with consequent reduction in pollution.
However, these advantages have not been realized primarily due to a failure in the prior art to teach an adequate means of sealing the combustion chamber. Therefore, the principles behind the planetary rotor engine have never been successfully developed for commercial use, primarily due to the heretofore unsolved problems of sealing the mechanism properly in order to provide the necessary operational efficiency.
To understand the seals of the present invention, the junctures needing sealing which are formed by components of a planetary rotor engine need be understood. More specifically, a seal of predetermined tolerance, from zero upwards, must be provided at three critical locations, namely, 1) the rotor faces, 2) the ends of the rotors and corresponding case ends, and 3) the rotor shafts. Until the present, static seals, which are typically interposed between the moving surface and usually a static component, have been tried and found unsuccessful. Therefore, a dynamic seal must be adapted to each of the three critical areas.
With respect first to the formation of the combustion volume between the plurality of moving rotor faces, a first dynamic seal must be defined to seal potential gaps as the rotor face surface translates across varying spatial coordinates to constantly reform the contact between a plurality of moving rotor surfaces and thereby define an enclosed combustion volume. Second, during any given operational cycle, the combustion volume is subjected to pulses caused by alternating combustion pressures and partial vacuums, the effect of which pulses must be considered at the juncture of the rotor ends and casing where an end space is formed. Through this end space, the pulses leak and adversely effect the centershaft seals supporting the rotor and casing (as well as engine performance, etc.). Thus, a second dynamic seal must be defined to effectively seal such space and minimize the adverse effect of alternating pulses leaking between the end space formed between the rotor end and the case. Third, the centershaft seal itself can be redesigned as a third dynamic seal to minimize the adverse pulse effects and increase its life by decreasing frictional thermal and wear conditions during low-pulse conditions (i.e. when high sealing forces are less necessary).
Moreover, the present invention considers and overcomes the problems of maintaining uniform and consistent dynamic seals as they undergo a plurality of physical effects during operation, including physical wear, thermal expansion and contraction of materials, and engine performance-related changes such as oscillating pressures and partial vacuums created during combustion cycles. Accordingly, the present invention responds to these problems and needs by providing both a method embodying the inventive principle necessary to effectively seal a planetary rotor engine, as well as, by providing various novel mechanisms embodying the principle. The method of the present invention establishes both rotor face and rotor end and shaft seals, i.e. the means, which provide the required sealing in order to allow the planetary rotor engine to be practicable.
The planetary rotor engines as a class are defined as exemplified by the following related art, but none has satisfactorily solved the problem of sealing the combustion chamber as it dynamically forms and reforms. One of the first was described in U.S. Pat. No. 710,756 issued on Oct. 7, 1902 to Thomas S. Colbourne, titled "Rotary Engine," wherein the rotors each have relatively sharp or pointed ends, which is no more than a special case of the smaller minor diameter arcs later used in such rotors. Colbourne is silent regarding any sealing means for his engine. Likewise, U.S. Pat. No. 1,349,882 issued on Aug. 17, 1920 to Walter A. Homan, titled "Rotary Engine," describes a planetary rotor mechanism of the pseudo-elliptical rotor configuration. Homan, however, recognizes the difficulty in sealing the working chamber of such machines, and attempts to solve the problem by providing a four way floating seal within the working chamber. Assuming the Homan roller device to be effective, it nevertheless decreases the efficiency of the planetary rotor machine to which it is applied, due to the volume it takes up within the working chamber of the machine, unlike the present rotor sealing means which requires no additional volume within the working chamber of the engine.
Not until U.S. Pat. No. 2,097,881 issued on Nov. 2, 1937 to Milton S. Hopkins, titled "Rotary Engine," is an essentially complete planetary rotor engine described, primarily directed to providing a valve mechanism for such an engine. Hopkins describes an engine having four pseudo-elliptical rotors and also describes the basic geometry of the configuration. Hopkins also recognizes the problem of sealing such engines, as noted in the first object of the invention on page 1, column 1, lines 12 through 21 of his patent. However, Hopkins is silent on the subject of sealing means for such engines, and provides no solution for the sealing problem he recognizes.
Since such realization, a large number of subsequent patents have described various attempts to seal the planetary rotor engine. U.S. Pat. No. 3,439,654 issued on Apr. 22, 1969 to Donald K. Campbell, Jr., titled "Positive Displacement Internal Combustion Engine," describes a planetary rotor mechanism configuration similar to that of the Colbourne '756 U.S. Patent discussed above. Campbell, Jr. discloses tip seals within his rotors, but does not disclose any means of compensating for thermal dimensional changes in his engine, nor any means of sealing the ends of the rotors and the shafts in the case. The present invention accomplishes all of these sealing means, with the means for sealing the faces of the rotors against one another, serving to compensate for thermal dimensional changes of the rotors and case during operation of the machine.
U.S. Pat. No. 3,809,026 issued on May 7, 1974 to Duane B. Snyder, titled "Rotary Vane Internal Combustion Engine," describes a multiple rotor planetary rotor engine including sealing means between the rotors. The sealing means between rotors comprises floating strips of seal material having thickened opposite edges. The relatively thicker edges preclude the escape of the seals from between adjacent rotors, as the relatively thinner central area is pinched between adjacent rotors. The present invention does not utilize any sealing means which is invasive to the central working chamber of the machine, as is the case with the Snyder device. Snyder also discloses rotor end seals, which are of conventional configuration and unlike the seals of the present invention.
U.S. Pat. No. 3,883,277 issued on May 13, 1975 to Leonard J. Keller, titled "Rotary Vane Device With Improved Seals," describes an eccentric vane machine using double rollers between the distal ends of each pair of vanes in the case. As the vanes move inwardly and outwardly as they revolve eccentrically, the rollers provide the proper geometry for the vanes and also seal the distal ends of the vanes. Thus, the roller sealing means define one end of each working chamber between each adjacent vane, whereas the sealing means for adjacent rotors of the present invention, does not involve any structure within or forming a part of the working chamber of the machine. Keller is silent regarding any sealing means between the ends of the vanes and the inner walls of the case, which sealing means are provided in the present invention.
U.S. Pat. No. 3,990,410 issued on Nov. 9, 1976 to Ehud Fishman, titled "Rotary Engine With Rotary Valve," describes an engine configuration having three generally triangular shaped planetary rotors, somewhat similar to one of the embodiments of the Delamere '341 U.S. Patent discussed further above. Fishman teaches sealing between adjacent rotors by means of hinged, outwardly biased seals extending about half way along each face of each of the rotors. Each seal bears against an unsealed portion of an adjacent rotor during rotation. Whereas the present sealing means could be applied to such generally triangular rotor planetary rotor devices as disclosed in the Fishman and Delamere U.S. Patents, it is not invasive to the working chamber of the machine, unlike the sealing means used in the machines of Fishman and Delamere. It is also noted that Fishman does not disclose any sealing means for the ends of his rotors, nor for the shaft exiting the case, as provided by the present invention.
U.S. Pat. No. 4,934,325 issued on Jun. 19, 1990 to Duane B. Snyder, titled "Rotary Internal Combustion Engine," describes a planetary rotor engine similar to those machines described in the U.S. Patents to Colbourne, Homan, Hopkins, Delamere, Campbell Jr., and Snyder, discussed above. The Snyder '325 Patent discloses a rotor sealing means similar to that disclosed in U.S. Pat. No. 3,809,026 to the same inventor, but using tension springs to bias the seals outwardly at all times. The seals are invasive into the working chamber of the machine, unlike the non-invasive seals used in the planetary rotor engine sealing means of the present invention.
U.S. Pat. No. 4,968,234 issued on Nov. 6, 1990 to Dietrich Densch, titled "Rotary Piston Machine With Sealing Elements," describes a three planetary rotor machines with the rotors each having an arcuate triangular shape, as in one of the embodiments of the Delamere U.S. Patent and of the Fishman U.S. Patent, both discussed above. Densch discloses an invasive sealing means between rotors essentially like that disclosed by Snyder in his '026 U.S. Patent, discussed above.
U.S. Pat. No. 5,271,364 issued on Dec. 21, 1993 to Duane P. Snyder, titled "Rotary Internal Combustion Engine," describes a planetary rotor engine similar to that disclosed in U.S. Pat. No. 4,934,325 to the same inventor, and discussed above. However, the rotor-to-rotor sealing means of the later '364 U.S. Patent is different from the invasive vane seals disclosed earlier, and comprise a plurality of flexible wiper strips disposed along one of the minor diameters or apices of each of the rotors. The present invention does not require any specialized or particular sealing means disposed on or between the rotor faces, as the sealing is accomplished by careful control of the spacing between adjacent rotors, which means is not disclosed by Snyder. Also, rotor end seals are disclosed, which are similar to the end seals described in the earlier '325 U.S. Patent to the same inventor. These end seals operate frictionally, unlike the rotor end seals of the present invention.
U.S. Pat. No. 5,341,782 issued on Aug. 30, 1994 to W. Biswell McCall et al., titled "Rotary Internal Combustion Engine," describes a planetary rotor configuration similar to those of the U.S. Patents to Colbourne, Homan, Hopkins, Delamere, Campbell Jr., and Snyder, discussed above. A different valve means is disclosed, which is beyond the scope of the present invention comprising sealing means for such machines; the present sealing means may be used with the McCall et al. and any of the other planetary rotor machines of record. McCall et al. disclose rotor end seals comprising circumferential rings which bear against the adjacent inner surface of the case. The present invention is different, in that the rotor end seal means does not bear frictionally against the adjacent case wall or surface.
Thus, as can be seen with respect to planetary rotor engines, seals for the plurality of moving rotor faces are generally invasive, and thus a first dynamic seal is needed to seal potential gaps as the rotor face surface translates across varying spatial coordinates to constantly reform the contact between a plurality of moving rotor surfaces and thereby define an enclosed combustion volume. Second, a second dynamic seal is needed and desired to effectively seal the end space to minimize the effect of alternating pulses leaking between the end space formed between the rotor end and the case. Third, a third dynamic seal is needed and desired around the centershaft to minimize the adverse pulse effects and increase life by decreasing frictional thermal and wear conditions during low-pulse conditions (i.e. when high sealing forces are less necessary).
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.